Simplified version of createSignal

createSignalExample.js

// Array to keep track of currently executing computations
const context = [];

// Function to add a computation (running) to the subscriptions of a signal
function subscribe(running, subscriptions) {
  // Add the computation to the subscriptions set
  subscriptions.add(running);
  // Add the subscriptions set to the dependencies of the computation
  running.dependencies.add(subscriptions);
}

// Function to create a signal with a given initial value
function createSignal(value) {
  // Set to store the computations subscribed to the signal
  const subscriptions = new Set();

  // Function to read the current value of the signal
  const read = () => {
    // Get the currently executing computation (if any)
    const running = context[context.length - 1];
    // If there's a running computation, subscribe it to the signal's subscriptions
    if (running) subscribe(running, subscriptions);
    // Return the current value of the signal
    return value;
  };

  // Function to update the value of the signal
  const write = (nextValue) => {
    // Update the value of the signal
    value = nextValue;

    // Iterate over the subscriptions and execute each one
    for (const sub of [...subscriptions]) {
      sub.execute();
    }
  };

  // Return a tuple containing the read and write functions
  return [read, write];
}